Abstract 1636: Anticancer drug-induced Jak2/Stat3 activation confers a survival advantage in lung cancer cells

Abstract

Chemotherapy may trigger survival signaling in cancer cells and the cells may change the response to chemotherapy. Here we found chemotherapeutics-induced Jak2/Stat3 signaling activation, by which cancer cells escape from death in human lung cancer PC14PE6AS2 (AS2) and H157 cells with constitutively activated Stat3 protein. Cisplatin, paclitaxel and epirubicin are important agents in lung cancer treatment and they are reactive oxygen species (ROS)-producing agents. In AS2 and H157 cells, we found that during the paclitaxel treatment, early Jak2 activation occurred and then Stat3 tyrosine phosphorylation upregulated early. But Stat3 serine phosphorylation was not significantly increased. When AS2 and H157 cells were treated with cisplatin and epirubicin, the Jak2/Stat3 activation was also observed, which can be blocked by AG490. It is indicated that chemotherapy, such as paclitaxel, cisplatin and epirubicin, may activate Jak2/Stat3 pathway. In AS2 cells, chemotherapeutics generated ROS, and the chemotherapy-induced Jak2/Stat3 activation was only effectively inhibited by mitochondrial ROS scavengers as rotenone and antimycin. The similar finding was also observed in H157 cells. It is said that “mild” mitochondrial uncoupling provides a survival benefit in cancer cells. In AS2 and H157 cells, pretreatment with the mitochondrial uncoupler carbonylcyanide-4-trifluoromethoxy-phenylhydrazone (FCCP) inhibited paclitaxel-induced mitochondrial ROS generation, abolished paclitaxel-induced Stat3 activation in AS2 and H157 cells, and augmented paclitaxel-induced mitochondrial membrane potential decrease. Thereafter, we classified AS2 and H157 cells as “FCCP-responsive” or “less mitochondrial uncoupling” cancer cells. So that mitochondrial coupling-mediated oxidative stress modulated paclitaxel-induced Jak2/Stat3 activation in AS2 and H157 cells. Subsequently, Stat3 activation by chemotherapeutics enhanced survivin expression in AS2 and H157 cells. Pretreatment with AG490, FCCP and rotenone blocked paclitaxel-induced survivin expression in a dose-dependent manner. Pretreatment with FCCP and rotenone also made AS2 and H157 cells more sensitive to the drug. Conclusively, anti-cancer drugs-induced Jak2/Stat3 activation confers a survival advantage in lung cancer AS2 and H157 cells via mitochondrial-coupling mediated ROS generation. This is a new phenomenon of cellular response to chemotherapeutics, by which cancer cells escape from drug-induced death. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1636.